Combine CSV files with Excel VBA - excel

Question

I have some csv files in one folder. They all contain 3 specific columns. The number of total columns and the order may vary.
I want to concatenate all 3 columns with an underscore and write them in a single column in the worksheet that is running the code.
Here is what I have so far:
Option Explicit
Sub test()
Dim i As Long
Dim LastRow As Long
Dim Columns()
Columns = Array("Column1", "Column2", "Column3")
'Find Columns by Name
For i = 0 To 2
Columns(i) = Rows(1).Find(What:=Columns(i), LookIn:=xlValues, LookAt:=xlWhole, _
MatchCase:=False, SearchFormat:=False).Column
Next i
'Debug.Print Columns(0)
'Debug.Print Columns(1)
'Debug.Print Columns(2)
LastRow = Cells(Rows.Count, "A").End(xlUp).Row
For i = 2 To LastRow
Cells(i, 1) = Cells(i, Columns(0)) & "_" & Cells(i, Columns(1)) & "_" & Cells(i, Columns(2))
Next i
End Sub
As you can see, this does what I want, but only for the active sheet.
I actually want to loop through all csv files in the same folder as the active sheet and write the results in the first sheet, first column of the sheet running the code (which is not a csv itself obviously).
How can I do this?
thanks!

Answer 1

This is a code that will loop through a folder
Sub Button1_Click()
Dim MyFile As String, Str As String, MyDir As String, Wb As Workbook
Set Wb = ThisWorkbook
'change the address to suite
MyDir = "C:\WorkBookLoop\"
MyFile = Dir(MyDir & "*.xls") 'change file extension
ChDir MyDir
Application.ScreenUpdating = 0
Application.DisplayAlerts = 0
Do While MyFile <> ""
Workbooks.Open (MyFile)
'do something here
MyFile = Dir()
Loop
End Sub

Answer 2

It depends how you are naming the worksheets you create from the CSV files. You could add all the worksheets to a collection and use a For...Each loop to execute the entire search and concatenate procedure within that loop. Note that you'd have to explicitly define the first sheet name as this won't change through successive loops:
Option Explicit
Sub test()
Dim i As Long
Dim LastRow As Long
Dim Columns()
Dim frontSheet as Worksheet
Dim wSheets as New Collection
Dim ws as Worksheet
Set frontSheet = Sheets("name of front sheet")
'Add all your CSV sheets to wSheets using the .Add() method.
For Each ws in wSheets
Columns = Array("Column1", "Column2", "Column3")
'Find Columns by Name
For i = 0 To 2
Columns(i) = ws.Rows(1).Find(What:=Columns(i), LookIn:=xlValues, LookAt:=xlWhole, _
MatchCase:=False, SearchFormat:=False).Column
Next i
'Debug.Print Columns(0)
'Debug.Print Columns(1)
'Debug.Print Columns(2)
LastRow = ws.Cells(Rows.Count, "A").End(xlUp).Row
For i = 2 To LastRow
frontsheet.Cells(i, 1) = ws.Cells(i, Columns(0)) & "_" & ws.Cells(i, Columns(1)) & "_" & ws.Cells(i, Columns(2))
Next i
Next ws
End Sub
It's often slow and labourious to open CSV files in excel but VBA can read them as text files using a TextStream. Furthermore, file scripting objects let you work with files and directories directly. Something like this might be a better approach if you don't need to keep the files in a worksheet afterwards:
Sub SearchFoldersForCSV()
Dim fso As Object
Dim fld As Object
Dim file As Object
Dim ts As Object
Dim strPath As String
Dim lineNumber As Integer
Dim lineArray() As String
Dim cols() As Integer
Dim i As Integer
Dim frontSheet As Worksheet
Dim frontSheetRow As Integer
Dim concatString As String
Set frontSheet = Sheets("name of front sheet")
frontSheetRow = 1
strPath = "C:\where-im-searching\"
Set fso = CreateObject("Scripting.FileSystemObject")
Set fld = fso.GetFolder(strPath)
For Each file In fld.Files
If (Right(file.Name, 3) = "csv") Then
Debug.Print file.Name
Set ts = file.OpenAsTextStream()
lineNumber = 0
Do While Not ts.AtEndOfStream
lineNumber = lineNumber + 1
lineArray = Split(ts.ReadLine, ",")
If (lineNumber = 1) Then
'We are at the first line of the .CSV so
'find index in lineArray of columns of interest
'Add extra ElseIf as required
For i = LBound(lineArray) To UBound(lineArray)
If lineArray(i) = "Column 1" Then
cols(1) = i
ElseIf lineArray(i) = "Column 2" Then
cols(2) = i
ElseIf lineArray(i) = "Column 3" Then
cols(3) = i
End If
Next i
Else
'Read and store the column of interest from this
'row by reading the lineArray indices found above.
concatString = ""
For i = LBound(cols) To UBound(cols)
concatString = concatString & lineArray(i) & "_"
Next i
concatString = Left(concatString, Len(concatString) - 1)
frontSheet.Cells(frontSheetRow, 1).Value = concatString
frontSheetRow = frontSheetRow + 1
End If
Loop
ts.Close
End If
Next file
End Sub
You can find more information on FileSystemObject and TextStream here.